Lab12: Making and Interpreting Dinosaur
Footprints

Alexander's method is used to calculate the
speed of an animal from itís footprints, when the time taken to make the
tracks is unknown. We will use this method, as well as conventional velocity
measurements, on the tracks of a (hopefully cooperative) chicken. We will
also reconstruct the anatomy of a trackmaker's feet from footprints.

PART 1. HUMAN LOCOMOTION

Selected students will walk and run along a length
of hallway. The number of strides taken will be noted (a stride is the
distance from a homologous part of one footstep of one foot to the next
footstep of the same foot) as well as the total distince traversed, and
the amount of time the traverse takes. Do it for walking and running.

1. Actual velocity of the student

Measure the veocity of the student during its
traverse (i. e. measure the distance the student walks and the time it
takes).

V = d/t

where:

V = velocity (m/s)d = distance traveled (m)t = time (s)

2. Velocity estimated from the footprint length
and stride length.

We will assume the footprint length would equal
the student's foot length.

Use Alexander's formula to calculate
the predicted velocity of the student:

The TA and the class will prepare a bed of clay
on which the theropod dinosaur (Gallus gallus - domestic chicken)
will walk. The chicken encouraged to walk or if we are lucky, run along
the clay. The amount of time the checken takes to traverse the clay bed
will be timed with a stopwatch, and the length of the traverse from homologous
points on the first and last track will be measured .

1. Actual velocity of the chicken

Measure the veocity of the chicken during
its traverse (i. e. measure the distance the chicken walks and the time
it takes) as you did for the student above.

2. Velocity estimated from the footprint
length and stride length.

Use Alexander's formula to calculate
the predicted velocity of the chicken as you did for the human.

3. Compare calculated speed with real speed.

Are they different and why?

PART 3. DINOSAURIAN SPEEDS

1. Use the outline drawing (Figure 2) to calculate
the speeds (in meters/sec) of the dinosaur tracks using the same methods
as above. Compare these speed estimates with those of the chicken. The
track type here is a small theropod track called Grallator.

PART 4. RECONSTRUCTING TRACKMAKERS FEET

1. Look at the dinosaur footprints we have out
and draw the outlines taking special care to accurately draw in the position
of the foot pads. Using Peabody's method (Figure 3), which states that
the pads of the track correspond to the joints between the bones (phalanges),
reconstruct the foot skeletons of Anchisauripus sp. and Anomoepus
sp. By comparison with the Allosaurus skeleton, label the digit
numbers, and determine whether the tracks are left or right (remember these
tracks are casts, not impressions). Which do you think is ornithischian
vs. saurischian?

2. Draw the footprint of Gallus gallus
and reconstruct its anatomy. Compare with the other dinosaur tracks.